Method and apparatus for interleaving data in a mobile communication system

ABSTRACT

An interleaving method to which time-first-mapping is applied for a plurality of channel-coded and rate-matched code blocks in a mobile communication system is provided. The interleaving method includes determining sizes of a horizontal area and a vertical area of an interleaver, generating modulation groups with adjacent coded bits in a vertical direction according to a modulation scheme, sequentially writing the modulation groups in the horizontal area on a row-by-row basis, and sequentially reading the coded bits written in the interleaver in the vertical area on a column-by-column basis.

PRIORITY

This application claims the benefit under 35 U.S.C. §119(a) of a Koreanpatent application filed in the Korean Intellectual Property Office onOct. 4, 2007 and assigned Serial No. 2007-100054, the entire disclosureof which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for transmittingdata in a next-generation mobile communication system. Moreparticularly, the present invention relates to a method and apparatusfor interleaving data in a mobile communication system.

2. Description of the Related Art

With respect to mobile communication systems, intensive research isbeing conducted on Orthogonal Frequency Division Multiple Access (OFDMA)and Single Carrier—Frequency Division Multiple Access (SC-FDMA) asschemes useful for high-speed data transmission in a wireless channel.

At present, 3^(rd) Generation Partnership Project (3GPP), the standardsgroup for asynchronous cellular mobile communications, is studying LongTerm Evolution (LTE) or the Evolved Universal Terrestrial Radio Access(E-UTRA) system, which is the next-generation mobile communicationsystem, based on the above-stated multiple access schemes.

A multiple access scheme generally allocates and manages time-frequencyresources on which it will carry data or control information for eachuser separately so that they do not overlap each other, i.e., they keeporthogonality, thereby distinguishing data or control information foreach user. For control channels, the multiple access scheme canadditionally allocate code resources, thereby distinguishing controlinformation for each user.

FIG. 1 is a diagram illustrating time-frequency resource and subframestructure for transmitting data or control information on an uplink in aconventional 3GPP LTE system. In FIG. 1, the horizontal axis representsa time domain and the vertical axis represents a frequency domain.

Referring to FIG. 1, the minimum transmission unit in the time domain isan SC-FDMA symbol. N_(symb) SC-FDMA symbols 102 constitute one slot 106and 2 slots constitute one subframe 100. The number N_(symb) of SC-FDMAsymbols is variable according to a length of a Cyclic Prefix (CP) thatis added to every SC-FDMA symbol for prevention of inter-symbolinterference. For example, N_(symb)=7 for a normal CP, and N_(symb)=6for an extended CP.

A length of the slot is 0.5 ms and a length of the subframe is 1.0 ms.The minimum transmission unit in the frequency domain is a subcarrier,and the entire system transmission band is composed of a total of NBWsubcarriers 104. N_(BW) is a value that is in proportion to the systemtransmission band. For example, N_(BW)=600 for the 10-MHz transmissionband.

In the time-frequency domain, the basic unit of resources is a ResourceElement (RE) 112, that can be indicated by a subcarrier index k and anSC-FDMA symbol index 1, wherein 1 has a value between 0 114 andN_(symb)−1 116. A Resource Block (RB) 108 is defined by N_(symb)consecutive SC-FDMA symbols 102 in the time domain and N_(RB)consecutive subcarriers 110 in the frequency domain. Therefore, one RB108 is composed of N_(symb)*N_(RB) REs 112. Resources for datatransmission are scheduled in the time domain by an Evolved Node B(ENB), also known as a Base Station (BS), in units of 2 consecutive RBs.

FIG. 2 is a diagram illustrating a subframe structure for N_(symb)=7 ina conventional 3GPP LTE system.

Referring to FIG. 2, a subframe 202, which is a basic transmission unitof the uplink, has a 1-ms length, and one subframe is composed of two0.5-ms slots 204 and 206. The slots 204 and 206 are each composed of aplurality of SC-FDMA symbols 211˜224. In an example of FIG. 2, in onesubframe 202, data is transmitted in SC-FDMA symbols indicated byreference numerals 211, 212, 213, 215, 216, 217, 218, 219, 220, 222, 223and 224, and pilots (also referred to as a Reference Signal (RS)) aretransmitted in SC-FDMA symbols indicated by reference numerals 214 and221. Therefore, for one subframe, there are a total of 12 SC-FDMAsymbols for data transmission. The pilot, composed of a predefinedsequence, is used for channel estimation for coherent demodulation atthe receiver. The number of SC-FDMA symbols for control informationtransmission, the number of SC-FDMA symbols for RS transmission, andtheir positions in the subframe are given herein by way of example, andthese are subject to change according to the system operation.

The LTE system employs turbo coding as an error correcting coding orchannel coding method for increasing reception reliability of data. Foroptimized realization, the maximum size Z of an input bit stream(hereinafter referred to as ‘code block’) of a turbo code may not exceed6144 bits. Therefore, when the amount of desired transmission data isgreater than 6144 bits, the LTE system segments the desired transmissiondata into a plurality of code blocks, and then channel-codes the codeblocks individually. It is characterized that a size of the code blockis a multiple of 8. The channel-coded code blocks each undergo ratematching on a code block by code block basis, so that their sizes areadjusted to be matched with the amount of allocated resources. There isan additional need for an interleaving operation for making the codeblocks be robust against a burst error on a wireless transmission path,and a modulation operation for increasing the spectral efficiency. Theinterleaving operation combines a plurality of code blocks and processesthem, and the modulation operation is performed on the code blocksindividually, thereby preventing the possible case where symbols ofdifferent code blocks constitute one modulation symbol.

However, a definition of the detailed interleaving operation is notgiven in the LTE system.

SUMMARY OF THE INVENTION

An aspect of the present invention is to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide an interleaving method and apparatus forincreasing reception reliability of transmission data in an LTE system.

According to one aspect of the present invention, an interleaving methodto which time-first-mapping is applied for a plurality of channel-codedand rate-matched code blocks in a mobile communication system isprovided. The interleaving method includes determining sizes of ahorizontal area and a vertical area of an interleaver, generatingmodulation groups with adjacent coded bits in a vertical directionaccording to a modulation scheme, sequentially writing the modulationgroups in the horizontal area on a row-by-row basis, and sequentiallyreading the coded bits written in the interleaver in the vertcal area ona column-by-column basis.

According to another aspect of the present invention, a deinterleavingmethod to which time-first-mapping is applied for a plurality ofchannel-coded and rate-matched code blocks in a mobile communicationsystem is provided. The deinterleaving method includes determining sizesof a horizontal area and a vertical area of a deinterleaver,sequentially writing an input signal of the deinterleaver on acolumn-by-column basis, generating modulation groups with the adjacentcoded bits in adjacent rows, written in the deinterleaver, according toa modulation scheme, and sequentially reading the modulation groups on arow-by-row basis.

According to further another aspect of the present invention, aninterleaving apparatus to which time-first-mapping is applied for aplurality of channel-coded and rate-matched code blocks in a mobilecommunication system is provided. The interleaving apparatus includes aninterleaver, a controller for determining sizes of a horizontal area anda vertical area of the interleaver, and for determining a modulationgroup generation method, a writer for reciving the modulation groupgeneration method from the controller, for generating modulation groupswith adjacent coded bits in a vertical direction according to modulationscheme, and for sequentially writing the modulation groups in theinterleaver in the horizontal area on a row-by-row basis, and a readerfor sequentially reading the coded bits written in the interleaver on acolumn-by-column basis.

According to further another aspect of the present invention, adeinterleaving apparatus to which time-first-mapping is applied for aplurality of channel-coded and rate-matched code blocks in a mobilecommunication system is provided. The deinterleaving apparatus includesa deinterleaver, a controller for determining sizes of a horizontal areaand a vertical area of the deinterleaver, and for determining amodulation group generation method, a writer for sequentially writing aninput signal in the deinterleaver on a column-by-column basis, and areader for receiving the modulation group generation method from thecontroller, for generating modulation groups in a vertical directionaccording to a modulation scheme, and for sequentially reading themodulation groups on a row-by-row basis.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a diagram illustrating time-frequency resource and subframestructure in a conventional LTE system;

FIG. 2 is a diagram illustrating an example of a subframe structure in aconventional LTE system;

FIG. 3 is a data transmission block diagram to which afrequency-first-mapping method is applied;

FIG. 4 is a data transmission block diagram to which atime-first-mapping method is applied;

FIG. 5 is a diagram illustrating an operating principle of a firstexemplary embodiment of the present invention;

FIG. 6 is a diagram illustrating an interleaving procedure in atransmitter according to the first exemplary embodiment of the presentinvention;

FIG. 7 is a diagram illustrating a deinterleaving procedure in areceiver according to the first exemplary embodiment of the presentinvention;

FIGS. 8A and 8B are diagrams illustrating a data transmission apparatusaccording to the first and a second exemplary embodiments of the presentinvention;

FIG. 9 is a diagram illustrating an internal structure of theinterleaver according to the first and second exemplary embodiments ofthe present invention;

FIGS. 10A and 10B are diagrams illustrating a data reception apparatusaccording to the first and second exemplary embodiments of the presentinvention;

FIG. 11 is a diagram illustrating an operating principle of the secondexemplary embodiment of the present invention;

FIG. 12 is a diagram illustrating an interleaving procedure in atransmitter according to the second exemplary embodiment of the presentinvention;

FIG. 13 is a diagram illustrating a deinterleaving procedure in areceiver according to the second exemplary embodiment of the presentinvention;

FIG. 14 is a diagram illustrating an operating principle of a thirdexemplary embodiment of the present invention;

FIG. 15 is a diagram illustrating an interleaving procedure in atransmitter according to the third exemplary embodiment of the presentinvention;

FIG. 16 is a diagram illustrating a deinterleaving procedure in areceiver according to the third exemplary embodiment of the presentinvention;

FIGS. 17A and 17B are diagrams illustrating a data transmissionapparatus according to the third exemplary embodiment of the presentinvention; and

FIGS. 18A and 18B are diagrams illustrating a data reception apparatusaccording to the third exemplary embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the present invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions are omitted for clarity and conciseness. Terms used hereinare defined based on functions in the exemplary embodiments of thepresent invention and may vary according to users, operators' intentionor usual practices. Therefore, the definition of the terms should bemade based on the contents throughout the specification.

Although a description of exemplary embodiments of the present inventionwill be made herein on an assumption that a User Equipment (UE), alsoknown as a Mobile Station (MS), transmits data on the uplink in acellular communication system based on the LTE system, it is noted thatthe present invention is not limited to a particular transmission systemor a transmission direction (uplink or downlink) of data.

With reference to FIGS. 3 and 4, an operating principle of exemplaryembodiments of the present invention will be described. When a number Nof code blocks are formed due to the large amount of information fordesired transmission data, a method for channel-coding and rate-matchingthe code blocks individually, and then mapping the code blocks to theallocated time-frequency resources can be classified into afrequency-first-mapping method and a time-first-mapping method.

With reference to a data transmission block diagram of FIG. 3, adescription will now be made of the frequency-first-mapping method.

FIG. 3 illustrates an example where the amount of time-frequencyresources 300 that a UE is allocated from an ENB is defined by referencenumeral 302 in the frequency domain and reference numeral 304 in thetime domain.

An ENB may allocate the time-frequency resources on asubframe-by-subframe basis. The frequency-first-mapping method mapssymbols in an arbitrary code block to the allocated time-frequencyresources in such a manner that it sequentially changes frequency-domainindexes with time-domain indexes fixed. When the frequency-domainindexes are all exhausted in a given time-domain index, thefrequency-first-mapping method sequentially increases the time-domainindexes and then preferentially performs symbol mapping again in thefrequency domain.

Referring to FIG. 3, a code block (0) 306 is mapped to the first SC-FDMAsymbol in the subframe 304 with the frequency-first-mapping method, anda code block (1) 308 is mapped to the second SC-FDMA symbol in thesubframe with the frequency-first-mapping method. Finally, a code block(N−2) 310 is mapped to the second to last SC-FDMA symbol in the subframeand a code block (N−1) 312 is mapped to the last SC-FDMA symbol in thesubframe with the frequency-first-mapping method.

In the following transmission procedure, the data is transmitted afterundergoing signal processing in a Discrete Fourier Transform (DFT) block314, a resource element mapper 316, and an Inverse Fast FourierTransform (IFFT) block 318.

The DFT block 314 reads input data in units of SC-FDMA symbols, andoutputs a frequency-domain signal through DFT signal processing. Theresource element mapper 316 maps a signal received from the DFT block314 to the frequency-domain resources allocated from the ENB in theentire system transmission band. An output signal of the resourceelement mapper 316 is transformed into a time-domain signal in the IFFTblock 318 through IFFT signal processing, and then converted into aserial signal by means of a parallel-to-serial (P/S) converter 320. A CPadder (or CP inserter) 322 adds a CP for inter-symbol interferenceprevention to the serial signal, and then transmits the CP-added datavia a transmit antenna 324.

However, in the foregoing frequency-first-mapping method, when thechannel environment where data is transmitted is subject to an abrupttime-dependent change within one subframe, a particular code block maybe lost as it suffers a poor channel environment. Channel coding is atechnology in which, even though partial data in the code block is lost,a receiver can receive the code block without error by using an errorcorrection capability of added redundant information. However, if all ora considerable part of the code block suffers a loss, the loss mayexceed the limit of the error correction capability, thereby making itimpossible to recover from the error. In this case, Hybrid AutomaticRepeat reQuest (HARQ) retransmission occurs, causing an unavoidablewaste of wireless resources.

Next, with reference to a data transmission block diagram of FIG. 4, thetime-first-mapping method will be described.

FIG. 4 illustrates an example in which the amount of time-frequencyresources 400 that a UE is allocated from an ENB is defined by referencenumeral 402 in the frequency domain and reference numeral 404 in thetime domain. The ENB may allocate the time-frequency resources on asubframe-by-subframe basis.

The time-first-mapping method maps symbols in an arbitrary code block tothe allocated time-frequency resources in such a manner that itsequentially changes time-domain indexes with frequency-domain indexesfixed. When the time-domain indexes are all exhausted in a givenfrequency-domain index, the time-first-mapping method sequentiallyincreases the frequency-domain indexes and then preferentially performssymbol mapping again in the time domain.

Referring to FIG. 4, a code block (0) 406 is mapped to the firstsubcarrier in the allocated frequency-domain resources with thetime-first-mapping method, and a code block (1) 408 is mapped to thesecond subcarrier in the allocated frequency-domain resources with thetime-first-mapping method. Finally, a code block (N−2) 410 is mapped tothe second to last subcarrier in the allocated frequency-domainresources with the time-first-mapping method. A code block (N−1) 412 ismapped to the last subcarrier in the allocated frequency-domainresources with the time-first-mapping method. In the followingtransmission procedure, the data is transmitted after undergoing signalprocessing in a DFT block 414, a resource element mapper 416, and anIFFT block 418. Since the signal processing procedure after the DFTblock 414 is equal to that in FIG. 3, a description thereof will beomitted herein.

The foregoing time-first-mapping method can noticeably reduce thepossibility that a particular code block may be completely lost as itexperiences the poor channel environment, even though the channelenvironment in which data is transmitted is subject to an abrupttime-dependent change within one subframe. That is, even though thechannel environment is very poor for a particular time period within onesubframe, it is restricted below the limit of the error correctioncapability from the standpoint of an arbitrary code block, so that thereceiver can recover the data without error. Thus, in this case, N codeblocks all suffer the loss within the limit of the error correctioncapability, thereby making it possible to recover the data withouterror. Therefore, the time-first-mapping method, compared with thefrequency-first-mapping method, is preferred to map N code blocks to thetime-frequency resources.

In defining the mapping method, exemplary embodiments of the presentinvention consider the modulation scheme being applied to the desiredtransmission data, thereby preventing the possible case where symbols ofdifferent code blocks constitute one modulation symbol. That is, inexemplary embodiments of the present invention, symbols constituting onemodulation symbol become symbols in the same code block. The mappingoperation can be equally realized with the interleaving operation.

A description will now be made of exemplary embodiments of thetime-first-mapping method or interleaving method where a modulationscheme is considered.

First Exemplary Embodiment

A first exemplary embodiment provides a detailed mapping operation orinterleaving operation to which the time-first-mapping method is appliedconsidering a modulation scheme for N code blocks that underwent channelcoding and rate matching.

FIG. 5 is a diagram illustrating an operating principle of a firstexemplary embodiment of the present invention.

Referring to FIG. 5, first, a rectangular interleaver having an R×C sizeis defined. R 502, a size of a row in the interleaver, is determined bya size N_(sc) _(—) _(alloc) of frequency-domain resources allocated froman ENB (R=N_(sc) _(—) _(alloc)). C 504, a size of a column in theinterleaver, is determined by the number N_(symb) of SC-FDMA symbolsconstituting one subframe and a modulation order M. That is,C=N_(symb)×log₂M. Regarding the modulation order M, M=4 for QuadraturePhase Shift Keying (QPSK), M=16 for 16-ary Quadrature AmplitudeModulation (16QAM), and M=64 for 64QAM, according to the modulationscheme. For N code blocks, a code block (0) 512 is composed of a totalof K(0) channel-coded and rate-matched symbols #0 to #K(0−1, a codeblock (1) 514 is composed of a total of K(1) channel-coded andrate-matched symbols #0 to #K(1−1, a code block (2) 516 is composed of atotal of K(2) channel-coded and rate-matched symbols #0 to #K(2−1, acode block (N-2) 518 is composed of a total of K(N−2) channel-coded andrate-matched symbols #0 to #K(N−2−1, and a code block (N−1) 520 iscomposed of a total of K(N−1) channel-coded and rate-matched symbols #0to #K(N−1−1.

The N code blocks are sequentially mapped in the R×C interleaver in sucha manner that the horizontal area of the interleaver is preferentiallyfilled by the time-first-mapping method. This is referred to as arow-by-row mapping scheme. If an intersection between an r^(th) positionof the vertical area and a c^(th) position of the horizontal area in theinterleaver is expressed as (r, c), the mapping operation starts from aposition (0, 0). For example, the first exemplary embodiment maps thefirst symbol of the code block (0) 512 to the position (0, 0) of theinterleaver, maps the second symbol to a position (0, 1) of theinterleaver, and performs symbol mapping to the last position (0, C-1)of the horizontal area by repeating the operation. Thereafter, the nextsymbol is mapped to a position (1, 0), which is an intersection betweena position increased by one in the vertical area of the interleaver andthe first position of the horizontal area, and maps the last symbol to aposition (1, C-1) of the interleaver by repeating the operation. Theoperation of disposing symbols of the code block in the interleaver isalso referred to as a write operation 506. The first symbol of the codeblock (1) 514 is mapped to a position (2, 0) which is the next positionof the position (1, C-1) where the last symbol of the code block (0) isdisposed, maps the second symbol to a position (2, 1) of theinterleaver, and maps the last symbol to a position (3, 3) by repeatingthe operation. By repeating the above process, the first symbol of thelast code block (N−1) 520 is mapped to a position (R-2, 2) which is thenext position of the position (R-2, 1) where the last symbol of the codeblock (N−2) is disposed, maps the second symbol to a position (R-2, 3)of the interleaver, and maps the last symbol to a position (R-2, C-1) byrepeating the operation.

After the N code blocks are all disposed in the interleaver,inter-column permutation 522 (an operation of permuting columns of theinterleaver) is performed, thereby ensuring robustness against apossible time-domain burst error.

When reading the code blocks that underwent inter-column permutationafter being mapped in the interleaver, modulation groups 510 aregenerated by grouping adjacent columns in units of log₂M taking themodulation scheme into account, and then column-by-column reading isperformed for sequentially reading the modulation groups from thevertical area. The reading operation 508 starts from the position (0, 0)of the interleaver. The operation of reading symbols of code blocks fromthe interleaver is also referred to as a read operation.

FIG. 5 illustrates an example where a QPSK modulation scheme is applied,and in this example, adjacent columns constitute modulation groups inunits of log₂M =2 from the QPSK modulation order M=4. The firstmodulation group read from the interleaver is composed of symbolsdisposed in the positions (0, 0) and (0, 1) of the interleaver, and thesecond modulation group is composed of symbols disposed in the positions(1, 0) and (1, 1), a vertical-area index that is increased by one fromthat of the first modulation group. Similarly, the last modulation groupread from the interleaver is composed of symbols disposed in thepositions (R-1, C-2) and (R-1, C-1).

FIG. 6 is a diagram illustrating an interleaving procedure in atransmitter according to the first exemplary embodiment of the presentinvention.

Referring to FIG. 6, the transmitter determines horizontal and verticalsizes of the interleaver in step 602. The transmitter determines thehorizontal size as C=N_(symb)×log₂M taking into account the number ofSC-FDMA symbols constituting one subframe and a modulation scheme, anddetermines the vertical size R as a size N_(sc) _(—) _(alloc) of thefrequency-domain resources allocated from an ENB. In step 604, thetransmitter sequentially writes coded symbols in each of code blocks inthe size-determined interleaver on a row-by-row basis. After completingthe writing operation on all code blocks, the transmitter performs aninter-column permutation operation on the written coded symbols in step606. The inter-column permutation operation is defined such thatadjacent columns are spaced as far as possible from each other. However,the transmitter performs a single-column permutation operation on thecolumns constituting one modulation group, thereby preventing thepossible case where symbols from different code blocks constitute onemodulation symbol in the later step.

In step 608, the transmitter generates modulation groups by selectinglog₂M coded symbols that are adjacent to each other along the columns inthe same code block in step 608, and sequentially reads the modulationgroups on a column-by-column basis in step 610, thereby completing theinterleaving operation.

FIG. 7 is a diagram illustrating a deinterleaving procedure in areceiver according to the first exemplary embodiment of the presentinvention.

Referring to FIG. 7, the receiver determines horizontal and verticalsizes of a deinterleaver in step 702. The receiver determines thehorizontal size as C=N_(symb)×log₂M taking into account the number ofSC-FDMA symbols constituting one subframe and a modulation scheme, anddetermines the vertical size R as a size N_(sc) _(—) _(alloc) of thefrequency-domain resources that an ENB allocates. In step 704, thereceiver generates modulation groups by grouping log₂M coded symbolsconstituting one modulation symbol on a row-by-row basis, for a receivedsignal. In step 706, the receiver sequentially writes the modulationgroups in the size-determined deinterleaver on a column-by-column basis.In step 708, the receiver performs on the written coded symbols aninter-column inverse permutation operation corresponding to an inverseoperation of the inter-column permutation operation used in theinterleaving procedure. Next, in step 710, the receiver sequentiallyreads the coded symbols on a row-by-row basis, thereby completing thedeinterleaving operation.

FIGS. 8A and 8B illustrate a data transmission apparatus to which thefirst and a second exemplary embodiments of the present invention areapplied.

Referring to FIG. 8A, data generated by a data generator 802, when asize of the data information is greater than a defined number of bits,is segmented into a plurality of code blocks in a code block segmentor804, and the code blocks are channel-coded by means of an encoder 806.The channel-coded code blocks are size-adjusted to be suitable to a sizeof the allocated time-frequency resources in a rate matching block 808,and then input to an interleaver 810. The interleaver 810, as describedabove, sequentially writes the input code blocks on a row-by-row basisby the time-first-mapping scheme, performs an inter-column permutationoperation thereon, and then sequentially reads modulation groups formedin the same code block on a column-by-column basis. A scrambler 812performs a permutation operation on the signal received from theinterleaver 810 in units of modulation groups, for inter-userrandomization, and a modulation mapper 814 performs a modulationoperation on the input signal. The modulated signal is converted into aparallel signal in a serial-to-parallel (S/P) converter 818 of FIG. 8B,that outputs the parallel signal to a DFT block 820. The DFT block 820reads the input data in units of SC-FDMA symbols, and outputs it as afrequency-domain signal through DFT signal processing. A resourceelement mapper 822 maps the signal received from the DFT block 820 tothe frequency-domain resources allocated from an ENB in the entiresystem transmission band. An output signal of the resource elementmapper 822 is transformed into a time-domain signal in an IFFT block 824through IFFT signal processing, and is then converted into a serialsignal by means of a P/S converter 826. A CP adder 828 adds a CP forinter-symbol interference prevention to the serial signal, and thentransmits the CP-added data via a transmit antenna 830.

FIG. 9 is a diagram illustrating an internal structure of theinterleaver, according to the first and second exemplary embodiments ofthe present invention.

Referring to FIG. 9, the interleaver includes an interleaver controller904, a writer 906, an interleaver memory 908, and a reader 910. Theinterleaver controller 904 acquires a size of time-frequency resourcesfor data transmission and a modulation scheme from scheduling allocationinformation 912, and determines a size of the interleaver memory 908depending on the acquired information. The writer 906 sequentiallywrites a signal stream 902 being input to the interleaver in theinterleaver memory 908 on a row-by-row basis by the time-first-mappingscheme. The reader 910 performs inter-column permutation on the signalstream written in the interleaver memory 908, sequentially readsgenerated modulation groups on a column-by-column basis and provides anoutput 914. The interleaver controller 904 provides the writer 906 withinformation such as size and writing order of each code block, and asize of the interleaver memory 908, to control an operation of thewriter 906, and provides the reader 910 with information such as adefinition of an inter-column permutation operation, a modulation groupgeneration method, a size of the interleaver memory 908, and readingorder, to control an operation of the reader 910.

FIGS. 10A and 10B illustrate a data reception apparatus to which thefirst and second exemplary embodiments of the present invention areapplied.

Referring to FIG. 10A, a signal received via an antenna 1002 is subjectto CP removal by means of a CP remover 1004, and the CP-removed signalis converted into a parallel signal by an S/P converter 1006, and theninput to a Fast Fourier Transform (FFT) block 1008. The FFT block 1008transforms the input signal into a frequency-domain signal by FFTtransforming. A resource element demapper 1010 extracts afrequency-domain signal to which desired data is mapped, from thefrequency-domain signal, and applies the extracted signal to an InverseDiscrete Fourier Transform (IDFT) block 1012. The signal input to theIDFT block 1012 is transformed into a time-domain signal by IDFT signalprocessing, and then converted into a serial signal by means of a P/Sconverter 1014. The serial signal is demodulated by a modulationdemapper 1018 of FIG. 10B, and a descrambler 1020 performs descramblingon the demodulated signal using an inverse operation of the scramblingoperation used in a transmitter, and then outputs the descrambled signalto a deinterleaver 1022. A detailed structure of an exemplarydeinterleaver 1022 is illustrated in FIG. 9. The deinterleaver 1022, asdescribed above, generates modulation groups on a row-by-row basis usingthe input signal stream according to a modulation scheme of thetransmitter, and then sequentially writes the modulation groups columnby column. Thereafter, the deinterleaver 1022 performs an inter-columninverse permutation operation thereon and sequentially reads codedsymbols row by row. The output signal is input to a rate dematchingblock 1024 for each code block, in which its size is adjusted to theoriginal code block size. The rate-dematched signal is decoded by adecoder 1026, and then concatenated to one data stream by a code blockconcatenator 1028, thereby achieving data acquisition of the information1030.

Meanwhile, it is also possible to obtain a similar effect as that of theforegoing operation by defining an interleaver given by rotating, by90°, the R×C rectangular interleaver and deinterleaver defined in thefirst exemplary embodiment. In this case, a horizontal size of theinterleaver and deinterleaver is determined as a size N_(sc) _(—)_(alloc) of the frequency-domain resources allocated from the ENB, and avertical size is determined as N_(symb)×log₂M from the number N_(symb)of SC-FDMA symbols constituting one subframe and a modulation order M.Therefore, the foregoing operations such as row-by-row writing, amodulation group generation method, an inter-column permutationoperation, and column-by-column reading, should be changed according toa definition of horizontal/vertical axes of the newly definedinterleaver and deinterleaver.

Second Exemplary Embodiment

A second exemplary embodiment provides another detailed mappingoperation or interleaving operation to which the time-first-mappingmethod is applied considering a modulation scheme for N code blocks thatunderwent channel coding and rate matching.

With reference to FIG. 11, a detailed operation of the second exemplaryembodiment will be described below.

First, a rectangular interleaver having an R×C size is defined. R 1102,a size of a row in the interleaver, is determined by a size N_(sc) _(—)_(alloc) of frequency-domain resources allocated from an ENB and amodulation order M. That is, R=N_(sc) _(—) _(alloc)×log₂M. Regarding themodulation order M, M=4 for QPSK, M=16 for 16QAM, and M=64 for 64QAM,according to the modulation scheme. C 1104, a size of a column in theinterleaver, is determined by the number N_(symb) of SC-FDMA symbolsconstituting one subframe. For N code blocks, a code block (0) 1112 iscomposed of a total of K(0) channel-coded and rate-matched symbols #0 to#K(0−1, a code block (1) 1114 is composed of a total of K(1)channel-coded and rate-matched symbols #0 to #K(1)−1, a code block (2)1116 is composed of a total of K(2) channel-coded and rate-matchedsymbols #0 to #K(2)−1, a code block (N−2) 1118 is composed of a total ofK(N−2) channel-coded and rate-matched symbols #0 to #K(N−2−1, and a codeblock (N−1) 1120 is composed of a total of K(N−1) channel-coded andrate-matched symbols #0 to #K(N−1)−1.

In the second exemplary embodiment, modulation groups 1110 are generatedin the vertical direction so that adjacent rows constitute onemodulation symbol by grouping symbols in each code block in units oflog₂M taking the modulation scheme into account, and then row-by-rowmapping is performed for sequentially mapping the modulation groups in ahorizontal area. The reading operation 1108 starts from the position (0,0) of the interleaver and the mapping operation starts from a position(0, 0) of the interleaver.

FIG. 11 illustrates an example where a QPSK modulation scheme isapplied, and in this example, adjacent rows constitute modulation groupsin units of log₂M=2 from the QPSK modulation order M=4. The firstmodulation group being mapped in the R×C interleaver is disposed inpositions (0, 0) and (1, 0) of the interleaver, and the secondmodulation group is disposed in positions (0, 1) and (1, 1), ahorizontal-area index of which is increased by one from that of thefirst modulation group. Similarly, the last modulation group beingmapped in the interleaver is disposed in positions (R-2, C-1) and (R-1,C-1). The operation of disposing is also referred to as a writeoperation 1106.

After the N code blocks are all disposed in the interleaver,inter-column permutation 1122 (an operation of permuting columns of theinterleaver) is performed, ensuring robustness against a possibletime-domain burst error.

When reading the code blocks that underwent inter-column permutationafter being mapped in the interleaver, column-by-column sequentialreading is performed. The reading operation starts from the position (0,0) of the interleaver. The first symbol being read from the interleaveris a symbol disposed in the position (0, 0) of the interleaver, thesecond symbol being read from the interleaver is a symbol disposed inthe position (1, 0), and the third symbol being read from theinterleaver is a symbol disposed in the position (2, 0). In this manner,the last symbol being read from the interleaver is a symbol disposed inthe position (R-1, C-1).

FIG. 12 is a diagram illustrating an interleaving procedure in atransmitter according to the second exemplary embodiment of the presentinvention.

Referring to FIG. 12, the transmitter determines horizontal and verticalsizes of an interleaver in step 1202. The transmitter determines thehorizontal size as C=N_(symb) taking into account the number of SC-FDMAsymbols constituting one subframe, and determines the vertical size R asR=N_(sc) _(—) _(alloc)×log₂M from the size N_(sc) _(—) _(alloc) of thefrequency-domain resources allocated from an ENB, and a modulation orderM. In step 1204, the transmitter selects log₂M adjacent coded symbols inthe same code block and generates modulation groups in the verticaldirection so that adjacent rows constitute one modulation symbol. Instep 1206, the transmitter sequentially writes the modulation groups inthe horizontal area on a row-by-row basis. After completing the writingoperation on all code blocks, the transmitter performs an inter-columnpermutation operation on the written coded symbols in step 1208. Theinter-column permutation operation is defined such that adjacent columnsare spaced as far as possible from each other. In step 1210, thetransmitter sequentially reads the symbols mapped in the interleaver ona column-by-column basis, thereby completing the interleaving operation.

FIG. 13 is a diagram illustrating a deinterleaving procedure in areceiver according to the second exemplary embodiment of the presentinvention.

Referring to FIG. 13, the receiver determines horizontal and verticalsizes of a deinterleaver in step 1302. The receiver determines thehorizontal size as C=N_(symb) taking into account the number of SC-FDMAsymbols constituting one subframe, and determines the vertical size R asR=N_(sc) _(—) _(alloc)×log₂M from the size N_(sc) _(—) _(alloc) of thefrequency-domain resources allocated from an ENB, and a modulation orderM. In step 1304, the receiver sequentially writes input symbols in thedeinterleaver on a column-by-column basis. In step 1306, the receiverperforms on the written coded symbols an inter-column inversepermutation operation corresponding to an inverse operation of theinter-column permutation operation performed in the interleavingprocedure. Next, in step 1308, the receiver generates modulation groupsby grouping log₂M symbols in adjacent rows taking the modulation schemeinto account. In step 1310, the receiver sequentially reads themodulation groups row by row, thereby completing the deinterleavingoperation.

Since a data transmission apparatus, an interleaver's internalapparatus, and a data reception apparatus, to which the second exemplaryembodiment is applied, are similar to those in the first exemplaryembodiment, a description thereof will be omitted for conciseness.However, the detailed interleaving/deinterleaving operation thereoffollows the description of the second exemplary embodiment.

It is also possible to obtain a similar effect as that of the foregoingoperation by defining an interleaver given by rotating, by 90°, the R×Crectangular interleaver and deinterleaver defined in the secondexemplary embodiment. In this case, a horizontal size of the interleaverand deinterleaver is determined as N_(sc) _(—) _(alloc)×log₂M from thesize N_(sc) _(—) _(alloc) of the frequency-domain resources allocatedfrom the ENB and the modulation order M, and the vertical size isdetermined as the number N_(symb) of SC-FDMA symbols constituting onesubframe. Therefore, the foregoing operations such as row-by-rowwriting, a modulation group generation method, an inter-columnpermutation operation, and column-by-column reading, should be changedaccording to a definition of horizontal/vertical axes of the newlydefined interleaver and deinterleaver.

Third Exemplary Embodiment

A third exemplary embodiment provides a detailed mapping operation orinterleaving operation to which the time-first-mapping method is appliedfor N modulated code blocks.

While the first exemplary embodiment and second exemplary embodimentprovide an operation to which the time-first-mapping method is appliedfor N channel-coded and rate-matched code blocks taking the modulationscheme into account, the third exemplary embodiment provides anoperation to which the time-first-mapping method is applied for N codeblocks that underwent modulation after channel coding and rate matching.

With reference to FIG. 14, a detailed operation of the third exemplaryembodiment will be described below.

Referring to FIG. 14, first, a rectangular interleaver having an R×Csize is defined. R 1402, a size of a row in the interleaver, isdetermined by the size N_(sc) _(—) _(alloc) of the frequency-domainresources allocated from an ENB. C 1404, a size of a column in theinterleaver, is determined by the number N_(symb) of SC-FDMA symbolsconstituting one subframe. For N code blocks, a code block (0) 1410 iscomposed of a total of K(0) channel-coded/rate-matched/modulated symbols#0 to #K(0) −1, a code block (1) 1412 is composed of a total of K(1)channel-coded/rate-matched/modulated symbols #0 to #K(1)−1, a code block(2) 1414 is composed of a total of K(2)channel-coded/rate-matched/modulated symbols #0 to #K(2)−1, a code block(N-2) 1416 is composed of a total of K(N−2)channel-coded/rate-matched/modulated symbols #0 to #K(N−2)−1, a codeblock (N−1) 1418 is composed of a total of K(N−1)channel-coded/rate-matched/modulated symbols #0 to #K(N−1)−1.

Row-by-row mapping is performed for sequentially mapping symbols in eachcode block in a horizontal area of the interleaver. The mappingoperation starts from a position (0, 0) of the interleaver. The firstsymbol being mapped in the R×C interleaver is disposed in the position(0, 0) of the interleaver, and the second symbol is disposed in theposition (0, 1), a horizontal-area index of which is increased by onefrom that of the first symbol. Similarly, the last symbol being mappedin the interleaver is disposed in the position (R-1, C-1). The operationof disposing is also referred to as a write operation 1406.

After the N code blocks are disposed in the interleaver, inter-columnpermutation 1420 (an operation of permuting columns of the interleaver)is performed, thereby ensuring robustness against a possible time-domainburst error.

When reading the code blocks that underwent inter-column permutationafter being mapped in the interleaver, column-by-column sequentialreading is performed. The reading operation 1408 starts from theposition (0, 0) of the interleaver. The first symbol being read from theinterleaver is a symbol disposed in the position (0, 0) of theinterleaver, the second symbol being read from the interleaver is asymbol disposed in the position (1, 0), the third symbol being read fromthe interleaver is a symbol disposed in the position (2, 0), and in thismanner, the last symbol being read from the interleaver is a symboldisposed in the position (R-1, C-1).

FIG. 15 is a diagram illustrating an interleaving procedure in atransmitter according to the third exemplary embodiment of the presentinvention.

Referring to FIG. 15, the transmitter determines horizontal and verticalsizes of an interleaver in step 1502. The transmitter determines thehorizontal size as C=N_(symb) taking into account the number of SC-FDMAsymbols constituting one subframe, and determines the vertical size R asthe size N_(sc) _(—) _(alloc) of the frequency-domain resourcesallocated from an ENB. In step 1504, the transmitter sequentially writessymbols in code blocks in the horizontal area on a row-by-row basis.After completing the writing operation on all the code blocks, thetransmitter performs an inter-column permutation operation on thewritten symbols in step 1506. The inter-column permutation operation isdefined such that adjacent columns are spaced as far as possible fromeach other. In step 1508, the transmitter sequentially reads the symbolsmapped in the interleaver on a column-by-column basis, therebycompleting the interleaving operation.

FIG. 16 is a diagram illustrating a deinterleaving procedure in areceiver according to the third exemplary embodiment of the presentinvention.

Referring to FIG. 16, the receiver determines horizontal and verticalsizes of a deinterleaver in step 1602. The receiver determines thehorizontal size as C=N_(symb) taking into account the number of SC-FDMAsymbols constituting one subframe, and determines the vertical size R asthe size N_(sc) _(—) _(alloc) of the frequency-domain resourcesallocated from an ENB. In step 1604, the receiver sequentially writesinput modulation symbols in the deinterleaver on a column-by-columnbasis. In step 1606, the receiver performs on the written coded symbolsan inter-column inverse permutation operation corresponding to aninverse operation of the inter-column permutation operation performed inthe interleaving procedure. Next, in step 1608, the receiversequentially reads symbols in the deinterleaver on a row-by-row basis,thereby completing the deinterleaving operation.

FIGS. 17A and 17B illustrate a data transmission apparatus to which thethird exemplary embodiment of the present invention is applied.

Referring to FIG. 17A, data generated by a data generator 1702, when asize of the data information is greater than a defined number of bits,is segmented into a plurality of code blocks in a code block segmentor1704, and the code blocks are channel-coded by means of an encoder 1706.The channel-coded code blocks are size-adjusted to be suitable to a sizeof the allocated time-frequency resources in a rate matching block 1708,and a modulation mapper 1710 performs a modulation operation on the codeblocks and outputs the results to an interleaver 1712. The interleaver1712, as described above, sequentially writes the input code blocks on arow-by-row basis by the time-first-mapping scheme, performs aninter-column permutation operation thereon, and then sequentially readsthem on a column-by-column basis. A scrambler 1714 performs apermutation operation on the signal received from the interleaver 1712,for inter-user randomization. The scrambled signal is converted into aparallel signal in an S/P converter 1718 of FIG. 17B, and then theparallel signal is output to a DFT block 1720. The DFT block 1720 readsinput data in units of SC-FDMA symbols, and outputs a frequency-domainsignal through DFT signal processing. A resource element mapper 1722maps the signal received from the DFT block 1720 to the frequency-domainresources allocated from an ENB in the entire system transmission band.An output signal of the resource element mapper 1722 is transformed intoa time-domain signal in an IFFT block 1724 through IFFT signalprocessing, and then converted into a serial signal by means of a P/Sconverter 1726. A CP adder 1728 adds a CP for inter-symbol interferenceprevention to the serial signal, and then transmits the CP-added datavia a transmit antenna 1730.

An internal structure of the interleaver 1712 follows the description ofFIG. 9. However, in the third exemplary embodiment, there is no need toconsider the modulation scheme in the interleaver.

FIGS. 18A and 18B illustrate a data reception apparatus to which thethird exemplary embodiment of the present invention is applied.

Referring to FIG. 18A, a signal received via an antenna 1802 is subjectto CP removal by means of a CP remover 1804, and the CP-removed signalis converted into a parallel signal by an S/P converter 1806, and theninput to an FFT block 1808. The FFT block 1808 transforms the inputsignal into a frequency-domain signal by FFT transforming. A resourceelement demapper 1810 extracts a frequency-domain signal to whichdesired data is mapped, from the frequency-domain signal, and appliesthe extracted signal to an IDFT block 1812. The signal input to the IDFTblock 1812 is transformed into a time-domain signal by IDFT signalprocessing, and then converted into a serial signal by means of a P/Sconverter 1814. As for the serial signal, a descrambler 1818 of FIG. 18Bperforms on the serial signal an inverse operation of the scramblingoperation used in a transmitter, and then inputs the descrambled signalto a deinterleaver 1820. The deinterleaver 1820, as described above,sequentially writes the input signal stream on a column-by-column basis,and then sequentially reads the symbols on a row-by-row basis afterperforming an inter-column inverse permutation operation. A modulationdemapper 1822 demodulates the signal received from the deinterleaver1820, and outputs the results to a rate dematching block 1824 for eachcode block, in which the size is adjusted to the original code blocksize. The rate-dematched signal is decoded by a decoder 1826, and thenconcatenated to one data stream by a code block concatenator 1828,thereby achieving data acquisition of the information 1830.

Meanwhile, it is also possible to obtain a similar effect as that of theforegoing operation by defining an interleaver given by rotating, by90°, the R×C rectangular interleaver and deinterleaver defined in thesecond embodiment. In this case, a horizontal size of the interleaverand deinterleaver is determined as the size N_(sc) _(—) _(alloc) of thefrequency-domain resource allocated from the ENB, and the vertical sizeis determined as the number N_(symb) of SC-FDMA symbols constituting onesubframe. Therefore, the foregoing operations such as row-by-rowwriting, an inter-column permutation operation, and column-by-columnreading, should be changed according to a definition ofhorizontal/vertical axes of the newly defined interleaver anddeinterleaver.

As is apparent from the foregoing description, exemplary embodiments ofthe present invention define a detailed interleaving operation fordesired transmission data in a mobile communication system, therebyreducing a bit error rate or block error rate for the data andincreasing reception reliability.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

1. An interleaving method to which time-first-mapping is applied for atleast one channel-coded and rate-matched code blocks in a mobilecommunication system, the method comprising: determining sizes of ahorizontal area and a vertical area of an interleaver; writing codedbits of modulation groups in the horizontal area of the interleaver on arow-by-row basis, the modulation groups comprising a number of codedbits and the number of coded bits being determined based on a modulationscheme; and reading the coded bits written in the interleaver from thevertical area of the interleaver on a column-by-column basis.
 2. Themethod of claim 1, wherein the size of the horizontal area correspondsto the number of symbols for data transmission constituting onesubframe.
 3. The method of claim 2, wherein the symbols comprise SingleCarrier-Frequency Division Multiple Access (SC-FDMA) symbols.
 4. Themethod of claim 1, wherein the size of the vertical area is definedbased on Log₂M, where M denotes a modulation order according to themodulation scheme.
 5. The method of claim 1, further comprising:performing inter-column permutation so that a space between adjacentcolumns of the written coded bits is maximized.
 6. The method of claim1, wherein the number of coded bits in each modulation group is log₂M,where M denotes a modulation order according to the modulation scheme.7. The method of claim 1, wherein an output of the interleaving methodis modulated after execution of the interleaving method.
 8. Adeinterleaving method to which time-first-mapping is applied for atleast one channel-coded and rate-matched code blocks in a mobilecommunication system, the method comprising: determining sizes of ahorizontal area and a vertical area of a deinterleaver; writing inputtedcoded bits in the vertical area of the deinterleaver on acolumn-by-column basis; and reading coded bits of modulation groups fromthe horizontal area of the deinterleaver on a row-by-row basis, themodulation groups comprising a number of coded bits, and the number ofcoded bits being determined based on a modulation scheme.
 9. The methodof claim 8, wherein the size of the horizontal area corresponds to thenumber of symbols for data transmission constituting one subframe. 10.The method of claim 8, wherein the size of the vertical area is definedbased on Log₂M, where M denotes a modulation order according to themodulation scheme.
 11. The method of claim 8, further comprising:performing inter-column inverse permutation when the inputted coded bitsunderwent inter-column permutation interleaving so that a space betweenadjacent columns of coded bits is maximized.
 12. The method of claim 8,wherein the number of coded bits in each modulation group is log₂M,where M denotes a modulation order according to the modulation scheme.13. The method of claim 8, wherein the inputted coded bits aredemodulated before execution of the deinterleaving method.
 14. Aninterleaving apparatus to which time-first-mapping is applied for atleast one channel-coded and rate-matched code blocks in a mobilecommunication system, the apparatus comprising: an interleaver; acontroller for determining sizes of a horizontal area and a verticalarea of the interleaver; a writer for writing coded bits of modulationgroups in the horizontal area of the interleaver on a row-by-row basis,the modulation groups comprising a number of coded bits and the numberof coded bits being determined based on a modulation scheme; and areader for reading the coded bits from the vertical area of theinterleaver on a column-by-column basis.
 15. The apparatus of claim 14,wherein the size of the horizontal area corresponds to the number ofsymbols for data transmission constituting one subframe.
 16. Theapparatus of claim 14, wherein the size of the vertical area is definedbased on Log₂M, where M denotes a modulation order according to themodulation scheme.
 17. The apparatus of claim 14, wherein the readerperforms an inter-column permutation operation so that a space betweenadjacent columns of the written coded bits is maximized.
 18. Theapparatus of claim 14, wherein the number of coded bits in eachmodulation group is log₂M, where M denotes a modulation order accordingto the modulation scheme.
 19. A deinterleaving apparatus to whichtime-first-mapping is applied for a plurality of channel-coded andrate-matched code blocks considering in a mobile communication system,the apparatus comprising: a deinterleaver; a controller for determiningsizes of a horizontal area and a vertical area of the deinterleaver; awriter for writing inputted coded bits in the vertical area of thedeinterleaver on a column-by-column basis; and a reader for readingcoded bits of modulation groups from the horizontal area of thedeinterleaver on a row-by-row basis, the modulation groups comprising anumber of coded bits and the number of coded bits being determined basedon a modulation scheme.
 20. The apparatus of claim 19, wherein the sizeof the horizontal area corresponds to the number of symbols for datatransmission constituting one subframe.
 21. The apparatus of claim 19,wherein the size of the vertical area is defined based on Log₂M, where Mdenotes a modulation order according to the modulation scheme.
 22. Theapparatus of claim 19, wherein the writer performs inter-column inversepermutation when the inputted coded bits underwent inter-columnpermutation interleaving so that a space between adjacent columns ofcoded bits is maximized.
 23. The apparatus of claim 19, wherein thenumber of coded bits in each modulation group is log₂M, where M denotesa modulation order according to the modulation scheme.